The X-ray Performance of Normal Fat Pad of Elbow and its Clinical Significance

Objective: To raise awareness on the X-ray performance of normal elbow fat pad. Methods: Analyzed 182 cases of X-ray performance on normal elbow fat pad. Observed the frequency of the fat pad occurrence, position, shape, and density on the standard lateral X-ray, and measured the maximum thickness. All the subjects were divided into two groups by age, 〈 18 years (juveniles) and ≥ 18 years (adult), and then male and female groups according to gender. All the data were collected for statistical analysis. Results: 182 cases were eligible for the study, including 132 adults and 50 juveniles. The anterior fat pads (AFP) were visible and the posterior fat pad (PFP) were invisible in all cases. In the normal lateral X-ray of elbow, the anterior fat pad was close to the distal end of the humerus and extrude to the front with a sharp triangle change angle of which points to the proximal end. The outer edge of AFP was straight,while the density was lower than the muscles and bones, surrounded The thickness value of AFP of juvenile s and adults were difference (t = 2.468, P = 0.015 ＜ 0.05); The thickness (3.42±0.71)mm and (3.13 ±0.70)mm with a obvious value of AFP of the male and female groups were (3.21 ±0.70) mm and (3.22± 0.73) mm with no difference (t = 0.085, P = 0.932 ＞ 0.05). The up and down limit of 95% reference range of AFP of adult were 4.50 mm and 1.76 mm. And the up and down limit of 95% reference range of AFP of juvenile were 4.81 mm and 2.03 mm. Conclusions: The anterior fat pad (AFP) was visible while the posterior was invisible. There was an obvious difference of thickness value of AFP between the juveniles and adults, but no difference between men and women. Correctly identifying of the X-ray of the performance of fat pad can greatly help to evaluate the condition of the elbow trauma patients.